The answer is e)15 Because : to find out the possibility of drawin yellow balls we should divide the number of yellow balls to total balls,
Let y be the number of yellow balls:
[tex]\frac { y }{ 30 } [/tex] and we know that the possibility is equal to [tex]\frac { 1 }{ 6 } [/tex]
[tex]\frac { y }{ 30 } =\frac { 1 }{ 6 } [/tex] from this equation we find y = 5.
If y=5 the number of red balls is 25. If we decrease red balls 15 total number of balls will be = 15. So since number of yellow balls did not change :[tex]\frac { 5 }{ 15 } =\frac { 1 }{ 3 } [/tex]
